The present invention relates in general to an ultrasonic sensing or scanning method, and in particular to a method of and a device for detecting or scanning objects, particularly original photographic copies processed in photographic devices, by means of an ultrasonic measuring apparatus.
From the German published patent application No. 26 42 633 a detecting device of this kind is known which senses the presence of sheets movable along a predetermined track. This prior-art device includes an ultrasonic generator which directs an ultrasonic field against the sheets movable in the track, and an ultrasonic receiver is arranged for receiving and evaluating ultrasonic energy transmitted by the generator. The ultrasonic generator and the ultrasonic receiver are located at opposite sides of the sheet track.
Known are also electrooptical sensing devices employing the so-called light barrier technique for detecting and scanning the objects. Also, mechanical feeling elements are known which upon contact with the sensed object change their position and are coupled to a device for recording this change.